Correlations between the leukocyte adherence inhibition microassay and in vivo tests of transplantation resistance.

The leukocyte adherence inhibition (LAI) microassay detects tumor-associated antigen(s). Extracts of colon carcinoma (MCA-38 and B16 melanoma tumors, both syngeneic to the C57BL/6J mice) are recognized only by peritoneal cells from mice bearing the corresponding tumor. To ascertain whether this in vitro antigenic recognition correlates with the ability of the host to recognize and reject a tumor in vivo, serial LAI microassays were performed synchronously with experiments designed to test the ability of mice bearing tumors to reject live secondary tumor challenges. Concomitant tumor immunity was present in the MCA-38 tumor-bearing mice on 3 occasions from 5 to 15 days from primary inoculation. In the B16 system, concomitant immunity was present on one occasion 10 days after primary inoculation. These results in turn were paralleled with the specific in vitro recognition of tumor antigens as detected by the LAI microassays. Loss of immunity in the "eclipse" phase of tumor development, as detected by concomitant tumor immunity, was paralleled by nonreactivity of the indicator cells in the LAI microassay.